End cover assembly, secondary battery, battery module, appratus, liquid-injection method and device

ABSTRACT

The present application provides an end cover assembly, a secondary battery, a battery module, a device, a liquid-injection method and a device thereof. The end cover assembly for the secondary battery includes: an end cover, provided with a through hole for injecting electrolyte, and including a connecting portion; a sealing assembly, configured to seal the through hole; a locking-fixing member, configured to be movable relative to the connecting portion in a radial direction of the through hole, so as to realize switching between a locked state and an unlocked state of the locking-fixing member and the connecting portion. In the locked state, the locking-fixing member presses against the sealing assembly to restrict the end cover to be separated from the sealing assembly; in the unlocked state, the end cover and the sealing assembly are separable to allow electrolyte to be injected from the through hole.

CROSS REFERENCE TO RELATED APPLICATION

The present application is a continuation of International ApplicationNo. PCT/CN2020/091108, filed on May 19, 2020, titled with “END COVERASSEMBLY, SECONDARY BATTERY, BATTERY MODULE, APPARATUS, LIQUID-INJECTIONMETHOD AND DEVICE”, which is hereby incorporated by reference in itsentirety.

TECHNICAL FIELD

The present application relates to a technical filed of battery, andspecifically relates to an end cover assembly, a secondary battery, abattery module, apparatus, a liquid injection method and a devicetherefor.

BACKGROUND

Because lithium-ion and other batteries have the advantages of highenergy density, high power density, multiple using cycles, and longstorage time, they have been widely used in electric vehicles.

The secondary battery includes a shell and an end cover assembly. Theshell is configured to receive electrolyte. The end cover assembly isconnected to the shell. During an operation process, the secondarybattery undergoes multiple charge-and-discharge cycles, it willinevitably lead to the partial irreversible reaction consumption of theelectrolyte, which will lead to a decrease in the usable capacity of thesecondary battery. If the electrolyte can be added to the inside of thesecondary battery during the operation process, it will be able toeffectively slow down the degree of capacity reduction and increase theoperation life of the secondary battery. However, in the related art,the assembled secondary battery cannot be refilled with the electrolyte,so that it will affects the operation life of the secondary battery.

SUMMARY

The present application provides an end cover assembly for a secondarybattery, including

-   -   an end cover, provided with a through hole for injecting        electrolyte, and including a connecting portion; a sealing        assembly, configured to seal the through hole; and a        locking-fixing member, configured to be movable relative to the        connecting portion in a radial direction of the through hole, so        as to realize switching between a locked state and an unlocked        state of the locking-fixing member and the connecting portion,        in which in the locked state, the locking-fixing member presses        against the sealing assembly to restrict the end cover from        being separated from the sealing assembly, and in the unlocked        state, the end cover and the sealing assembly are separable to        allow electrolyte to be injected from the through hole.

The end cover assembly in the embodiments of the present application canbe applied to a secondary battery, a predetermined amount of electrolytecan be injected into the secondary battery through the through hole,then the sealing assembly can seal the through hole, and finally thelocking-fixing member can lock the connecting portion of the end cover.After the secondary battery is used for a predetermined period of time,the locking-fixing member unlocks the connecting portion of the endcover, and then the sealing assembly is removed to open the throughhole. The predetermined amount of electrolyte can be replenished intothe secondary battery through the through hole. After completing theelectrolyte replenishment process, the sealing assembly seals thethrough hole, and the locking-fixing member locks the connecting portionof the end cover again, and the secondary battery can continue to beused normally. Thus, the secondary battery in the embodiments of thepresent application can be re-filled with the electrolyte afterassembled, which can effectively prolong the operation life of thesecondary battery.

Moreover, the embodiments of the present application provide a secondarybattery including the end cover assembly as described above.

Furthermore, the embodiments of the present application provide abattery module including the secondary battery as described above.

Still furthermore, the embodiments of the present application providesan apparatus including the secondary battery as described above forsupplying electrical power.

Still furthermore, the embodiments of the present application provide aliquid-injection method for the secondary battery, including

-   -   providing the end cover, in which the end cover includes the        through hole and the connecting portion,    -   injecting electrolyte through the through hole;    -   providing the sealing assembly;    -   mounting the sealing assembly to the end cover;    -   providing the locking-fixing member, and moving the        locking-fixing member toward a direction close to the connecting        portion in a radial direction of the through hole, so that the        locking-fixing member locks the connecting portion to restrict        the end cover being separated from the sealing assembly.

Still furthermore, the embodiments of the present application provide aliquid-injection device, for injecting the electrolyte into thesecondary battery as described above, the device including

-   -   a liquid injection component, configured to inject the        electrolyte into the through hole; and    -   a dismounting-and-mounting component for the locking-fixing        member, configured to move the locking-fixing member toward a        direction close to the connecting portion in the radial        direction of the through hole in the unlocked state, so that the        locking-fixing member locks the connecting portion to restrict        the end cover being separated from the sealing assembly; or        configured to move the locking-fixing member toward a direction        away from the connecting portion in the radial direction of the        through hole, so that the locking-fixing member unlocks the        connecting portion.

BRIEF DESCRIPTION OF THE DRAWINGS

The features, the advantages, and the technical effects in the exemplaryembodiments of the present application will be described below withreference to the drawings.

FIG. 1 shows a structural schematic view of a vehicle according to theembodiments of the present application;

FIG. 2 shows an exploded structural schematic view of a battery packaccording to an embodiment of the present application;

FIG. 3 shows a partial structural schematic view of a battery module setaccording to an embodiment of the present application;

FIG. 4 shows an exploded structural schematic view of a secondarybattery according to an embodiment of the present application;

FIG. 5 shows a partial exploded structural schematic view of an endcover assembly according to an embodiment of the present application;

FIG. 6 shows an enlarged view of a portion A in FIG. 5;

FIG. 7 is a structural schematic top view of the end cover assembly ofthe embodiment shown in FIG. 5 in an assembling state;

FIG. 8 shows a cross-sectional structural schematic view at a line B-Bin FIG. 7;

FIG. 9 shows a cross-sectional structural schematic view at a line C-Cin FIG. 7;

FIG. 10 shows an enlarged view of a portion D in FIG. 8;

FIG. 11 shows a partial exploded structural schematic view of an endcover assembly according to another embodiment of the presentapplication;

FIG. 12 shows an enlarged view of a portion E in FIG. 11;

FIG. 13 is a structural schematic top view of the end cover assembly ofthe embodiment shown in FIG. 11 in an assembling state;

FIG. 14 shows a cross-sectional structural schematic view at a line F-Fin FIG. 13;

FIG. 15 shows an enlarged view of a portion G in FIG. 14.

In the drawings, the drawings are not drawn to the actual scale.

REFERENCE SIGNS

1 vehicle;

10 battery pack;

20 battery module set;

30 secondary battery; 31 shell; 32 electrode assembly; 321 main body;321 a end face; 322 tab;

40 end cover assembly;

50 end cover; 50 a through hole; 50 b concave slot; 50 c electrodelead-out hole; 51 connecting portion; 511 snapping slot; 511 aposition-limiting wall; 52 body portion;

60 sealing assembly; 61 position-limiting member; 611 pressing-againstportion; 612 position-limiting portion; 613 supporting portion; 614accommodating slot; 62 sealing member;

70 locking-fixing member; 71 opening; 72 accommodating space;

80 electrode terminal;

90 adapter component;

X axial direction; Y peripheral direction.

DETAILED DESCRIPTION

The implementation of the present application will be described infurther detail below in conjunction with the drawings and embodiments.The detailed description and drawings of the embodiments below are usedto exemplarily illustrate the principle of the present application, butcannot be used to limit the scope of the present application, that is,the present application can be not limited to the described embodiments.

In the description of the present application, it should be noted that,unless otherwise specified, “plurality” means more than two; the terms“upper”, “lower”, “left”, “right”, “inner”, “outer”, etc. indicate theorientation or positional relationship only for the convenience ofdescribing the present application and simplifying the description,rather than indicating or implying that the device or the elementreferred to must have a specific orientation, be configured and operatedin a specific orientation, and therefore cannot be understood as alimitation of the present application. In addition, the terms “first”,“second”, “third”, etc. are only used for descriptive purposes, andcannot be understood as indicating or implying relative importance. Theterm “perpendicular” does not mean strictly perpendicular, but withinthe allowable range of error. The term “parallel” does not mean strictlyparallel, but within the allowable range of error.

The orientation words appearing in the following description are alldirections shown in the drawings, and do not limit the specificstructure of the present application. In the description of the presentapplication, it should also be noted that, unless otherwise clearlyspecified and limited, the terms “mount”, “communicate” and “connect”should be understood in a broad sense, for example, it can be a fixedconnection, a detachable connection, or an integral connection, it canbe a direct connection, or it can be connected indirectly through anintermedium. For those of ordinary skill in the art, the specificmeaning of the above-mentioned terms in the present application can beunderstood according to specific situations.

In order to better understand the present application, the embodimentsof the present application will be described below in conjunction withFIG. 1 to FIG. 15.

The embodiment of the present application provides a device using asecondary battery 30 as a power source. The device can be, but is notlimited to, a vehicle, a ship, an aircraft or the like. As shown in FIG.1, the embodiment of the present application provides the vehicle 1including a vehicle main body and a battery module. The battery moduleis arranged in the vehicle main body. Herein, the vehicle 1 may be apure electric vehicle, a hybrid electric vehicle or an extended-rangevehicle. The vehicle main body is provided with a driving motorelectrically connected to the battery module. The battery module cansupply electrical power to the driving motor. The driving motor isconnected to wheels in the vehicle main body through a transmissionmechanism to drive the vehicle to travel forward. Optionally, thebattery module may be horizontally arranged at a bottom of the vehiclemain body.

As shown in FIG. 2, the battery module may be a battery pack 10. Thereare many ways to arrange the battery pack 10. In some optionallyembodiments, the battery pack 10 includes a housing and the batterymodule set 20 arranged in the housing. The number of battery module set20 is one or more. One or more battery module sets 20 are arranged inthe housing in array. The type of housing is not limited. The housingcan be a frame-shaped housing, a disk-shaped housing, a box-shapedhousing or the like. Optionally, the housing includes a lower housingfor accommodating the battery module set 20 and an upper housing coveredwith the lower housing. The upper housing and the lower housing arecovered and closed with each other to form an accommodating portion forreceiving the battery module set 20. In another optional embodiment, thebattery pack 10 includes the housing and a plurality of secondarybatteries 30 directly arranged in the housing.

As shown in FIG. 3, the battery module may also be the battery moduleset 20, and the plurality of battery module sets 20 are arranged in thehousing and mounted on the vehicle main body.

As shown in FIG. 3, the battery module set 20 includes the plurality ofsecondary batteries 30. There are many ways to arrange the batterymodule set 20. In an embodiment, the battery module set 20 includes theaccommodating portion and the plurality of secondary batteries 30located in the accommodating portion. The plurality of secondarybatteries 30 are arranged side by side in the accommodating portion.There are many ways to arrange the accommodating portion, for example,the accommodating portion includes a shell and a cover plate arranged atthe shell; or the accommodating portion includes side plates and endplates that are successively connected with one another to enclose; orthe accommodating portion includes end plates arranged opposite eachother and a band around the outside of the secondary battery 30 and theend plates.

After noticing the problem that the operation life of the secondarybattery 30 is short and the secondary battery 30 cannot be reused, theapplicant has conducted the research and the analysis on the variousstructures of the secondary battery 30. The applicant found that thereis irreversible reaction consumption of electrolyte of the secondarybattery 30, resulting in a decrease in a using capacity of the secondarybattery 30. At the same time, if the electrolyte can be replenished, thedegree of the reduction of the capacity of the secondary battery 30 willbe effectively slowed down. However, since the factors such as thesafety, the sealing and the like need to be considered in an existingstructural design of the secondary battery 30, the assembled secondarybattery 30 cannot be refilled with the electrolyte.

Based on the above-mentioned problems discovered by the inventors, theinventors has improved the structure of the secondary battery 30, andthe embodiments of the present application will be further describedbelow.

As shown in FIG. 4, the secondary battery 30 in the embodiments of thepresent application includes a shell 31 and an electrode assembly 32arranged in the shell 31. The shell 31 in the embodiments of the presentapplication has a cuboid structure or other shapes. The shell 31 has aninternal space for receiving the electrode assembly 32 and theelectrolyte, and an opening communicating with the internal space. Theshell 31 may be made of materials such as aluminum, aluminum alloy,plastic or the like. The electrode assembly 32 in the embodiments of thepresent application can be formed by stacking or winding a firstelectrode sheet, a second electrode sheet and a separator locatedbetween the first electrode sheet and the second electrode sheet andserving as an insulator between the first electrode sheet and the secondelectrode sheet. In this embodiment, exemplarily, the first electrodesheet is the positive electrode sheet, and the second electrode sheet isthe negative electrode sheet. Each of the positive electrode sheet andthe negative electrode sheet includes a coated region and an uncoatedregion. A positive electrode sheet active material coats the coatedregion of the positive electrode sheet, and a negative electrode sheetactive material coats the coated region of the negative electrode sheet.On the coated region, the active material coats a current collectorformed by a thin-plate metal foil, and the active material does not coatthe uncoated region. After being wound or stacked, the electrodeassembly 32 includes two tabs 322 which are a positive tab and anegative tab respectively. The coated region of the positive electrodesheet and the coated region of the negative electrode sheet form a mainbody 321. The uncoated regions of the positive electrode sheets arestacked to form the positive tab, and the uncoated regions of thenegative electrode sheets are stacked to form the negative tab. In theembodiments of the present application, the main body 321 has two endfaces 321 a arranged to be opposite to each other in a length direction,and the positive electrode tab and the negative electrode tabrespectively extend beyond the two opposite end faces 321 a of the mainbody 321 in the length direction.

As shown in FIG. 4, the secondary battery 30 in the embodiments of thepresent application further includes an end cover assembly 40 sealinglyconnected to the shell 31. The end cover assembly 40 includes an endcover 50, electrode terminal 80, an adapter component 90, sealingassembly 60 and a locking-fixing member 70. The electrode terminal 80 isarranged on the end cover 50. The electrode terminal 80 is electricallyconnected to the tab 322 of the electrode assembly 32 through theadapter component 90. The shape of the electrode terminal 80 may besquare or circle, which is not limited here.

As shown in FIG. 5 and FIG. 6, the end cover 50 in the embodiments ofthe present application is provided with an electrode lead-out hole 50c. The electrode lead-out hole 50 c penetrates the end cover 50. Theelectrode terminal 80 is arranged on the end cover 50 and covers theelectrode lead-out hole 50 c. The end cover 50 is also provided with athrough hole 50 a for injecting electrolyte. The through hole 50 a andthe electrode lead-out hole 50 c are arranged to be spaced apart fromeach other. The end cover 50 has a connecting portion 51. The sealingassembly 60 is configured to seal the through hole 50 a on the end cover50. The locking-fixing member 70 is configured to be movable relative tothe connecting portion 51 of the end cover 50 in a radial direction ofthe through hole 50 a, so as to switch between a locked state and anunlocked state of the locking-fixing member 70 and the connectingportion 51. The radial direction of the through hole 50 a refers to adirection perpendicular to an axial direction X of the through hole 50a. When the locking-fixing member 70 and the connecting portion 51 arein the locked state, the locking-fixing member 70 presses against thesealing assembly 60 to restrict the end cover 50 from being separatedfrom the sealing assembly 60. When the locking-fixing member 70 and theconnecting portion 51 are in the unlocked state, the end cover 50 andthe sealing assembly 60 are separable to allow the electrolyte to beinjected from the through hole 50 a.

In the secondary battery 30 in the embodiments of the presentapplication, a predetermined amount of electrolyte can be injected intothe secondary battery 30 through the through hole 50 a, then the sealingassembly 60 can seal the through hole 50 a, and finally thelocking-fixing member 70 can lock the connecting portion 51 of the endcover 50. After the secondary battery 30 is used for a predeterminedperiod of time, the locking-fixing member 70 unlocks the connectingportion 51 of the end cover 50, and then the sealing assembly 60 isremoved to open the through hole 50 a. The predetermined amount ofelectrolyte can be replenished into the secondary battery 30 through thethrough hole 50 a. After completing the electrolyte replenishmentprocess, the sealing assembly 60 seals the through hole 50 a, and thelocking-fixing member 70 locks the connecting portion 51 of the endcover 50 again, and the secondary battery 30 can continue to be usednormally. Thus, the secondary battery 30 in the embodiments of thepresent application can be re-filled with the electrolyte afterassembled, which can effectively prolong the operation life of thesecondary battery 30.

In an embodiment, as shown in FIG. 6, the locking-fixing member 70 hasan opening 71 and an accommodating space 72 communicating with eachother. The connecting portion 51 is configured to enter theaccommodating space 72 through the opening 71. When the locking-fixingmember 70 moves in the radial direction of the through hole 50 a, theconnecting portion 51 enters the accommodating space 72 through theopening 71. After the connecting portion 51 enters the accommodatingspace 72, the locking-fixing member 70 locks the connecting portion 51.When the locking-fixing member 70 moves in the radial direction of thethrough hole 50 a, the connecting portion 51 can move out of theaccommodating space 72 through the opening 71, so that thelocking-fixing member 70 and the connecting portion 51 can be unlocked.In an example, a part of the locking-fixing member 70 where the opening71 is formed has the good ability of the elastic deformation. The sizeof the opening 71 of the locking-fixing member 70 is smaller than thesize of the accommodating space 72. The size of the opening 71 of thelocking-fixing member 70 is smaller than the size of the connectingportion 51, so that when the connecting portion 51 enters the opening 71or the connecting portion 51 moves out of the opening 71, the size ofthe opening 71 will become larger to provide a position to theconnecting portion 51, and the connecting portion 51 can pass throughthe opening 71 smoothly. A part of the locking-fixing member 70 wherethe accommodating space 72 is formed also has the good ability of theelastic deformation. After the connecting portion 51 enters theaccommodating space 72, the part of the locking-fixing member 70 wherethe accommodating space 72 is formed will return to an original state,so that the locking-fixing member 70 can lock the connecting portion 51of the end cover 50 through the part of the locking-fixing member 70where the accommodating space 72 is formed. After the connecting portion51 enters the accommodating space 72, the locking-fixing member 70 isnot easy to move in the radial direction of the through hole 50 a, sothat the connecting portion 51 is not easily detached from the opening71.

In an embodiment, as shown in FIG. 6, the locking-fixing member 70 issnap-fitted with the connecting portion 51 of the end cover 50, so thatthe locking-fixing member 70 and the connecting portion 51 are in thelocked state. The locking-fixing member 70 is detachably connected tothe connecting portion 51 of the end cover 50 by means of the snappingconnection, so that the locking-fixing member 70 and the connectingportion 51 can be quickly locked or unlocked to separate.

In an embodiment, as shown in FIG. 6, the connecting portion 51 of theend cover 50 is provided with a snapping slot 511, and at least a partof the locking-fixing member 70 is located in the snapping slot 511 torestrict the locking-fixing member 70 from moving in the axial directionX of the through hole 50 a. During the operation process of thesecondary battery 30, the secondary battery 30 may vibrate or impact inthe axial direction X of the through hole 50 a. Since the locking-fixingmember 70 is restricted by the connecting portion 51, the locking-fixingmember 70 and the connecting portion 51 are less likely to moverelatively to each other in the axial direction X of the through hole 50a, thereby reducing the possibility that the locking-fixing member 70and the connecting portion 51 are disconnected or loosen with each otherbecause of the movement of the locking-fixing member 70 in the axialdirection X of the through hole 50 a, and reducing the possibility thatthe sealing is failed and the electrolyte overflows from the throughhole 50 a because of the movement of the sealing assembly 60 in theaxial direction X of the through hole 50 a. In an example, the snappingslot 511 has a position-limiting wall 511 a for resisting against thelocking-fixing member 70 in the axial direction. A surface of thelocking-fixing member 70 away from the end cover 50 is in contact withthe position-limiting wall 511 a, and the locking-fixing member 70 andthe position-limiting wall 511 a are in a surface-to-surface contact.

In an embodiment, as shown in FIG. 6, the sealing assembly 60 includes aposition-limiting member 61 and a sealing member 62. The sealing member62 is arranged between the position-limiting member 61 and the end cover50, and seals the through hole 50 a. After the locking-fixing member 70is connected to the connecting portion 51, the locking-fixing member 70can press against the position-limiting member 61, so that thelimiting-fixing member 61 exerts a compressive stress on the sealingmember 62, thereby restricting the sealing member 62 from moving in theaxial direction X of the through hole 50 a, so that the sealing member62 can seal the through hole 50 a. In an example, referring to FIGS. 7to 9, a part of the sealing member 62 extends into the through hole 50a, and another part of the sealing member 62 is located outside thethrough hole 50 a. The part of the sealing member 62 extending into thethrough hole 50 a is in an interference fit with the through hole 50 a,and the part located outside the through hole 50 a covers the throughhole 50 a, thereby improving the sealing performance of the sealingmember 62. Optionally, the material of the sealing member 62 may be therubber or the silicone. In an example, as shown in FIG. 6 and FIG. 9,the position-limiting member 61 includes a pressing-against portion 611and a position-limiting portion 612. The pressing-against portion 611 isconnected to the position-limiting portion 612 and covers at least apart of the sealing member 62. In some embodiments, the pressing-againstportion 611 covers the entire sealing member 62. At least part of theposition-limiting portion 612 is located at a side of the locking-fixingmember 70 close to the end cover 50. The locking-fixing member 70presses against the position-limiting portion 612 to restrict the endcover 50 from being separated from the sealing assembly 60. Thelocking-fixing member 70 exerts the compressive stress in the axialdirection X of the through hole 50 a to a surface of theposition-limiting portion 612 away from the end cover 50 from a side ofthe position-limiting portion 612 away from the end cover 50, and thepressing-against portion 611 exerts a compressive stress in the axialdirection X of the through hole 50 a to the sealing member 62, so thatthe pressing-against portion 611 presses and fixes the sealing member62.

In one embodiment, referring to FIG. 6 and FIG. 9, the end cover 50further includes a body portion 52. The connecting portion 51 is a bossprotruding from a surface of the body portion 52. The through hole 50 apenetrates the connecting portion 51 and the body portion 52. At leastpart of the sealing member 62 is located at a side of the connectingportion 51 in the axial direction X of the through hole 50 a. In anexample, the body portion 52 has a rectangular plate-shaped structure.The connecting portion 51 includes a middle column-shaped portion andtwo columns. The two columns are located at two opposite sides of themiddle column-shaped portion, that is, the middle column-shaped portionis located between the two columns. The through hole 50 a penetrates themiddle column-shaped portion. The snapping slots 511 are respectivelyformed in the two columns. Optionally, the two columns are evenly spacedapart from each other in the peripheral direction Y of the through hole50 a. The locking-fixing member 70 has an annular structure. Thelocking-fixing member 70 is snap-fitted in the snapping slots 511 in thetwo columns, so as to be in a locked state with the connecting portion51. When locking or unlocking the locking-fixing member 70 and theconnecting portion 51, an auxiliary tool can be used to expand theopening 71 of the locking-fixing member 70 in advance, so that the twocolumns can pass through the opening 71 into the accommodating space 72or move out of the accommodating space 72 smoothly.

In an embodiment, referring to FIGS. 6 and 10, the position-limitingmember 61 further includes a supporting portion 613 and an accommodatingslot 614. The supporting portion 613 is connected to thepressing-against portion 611 and the position-limiting portion 612. Theaccommodating slot 614 penetrates the supporting portion 613 in theradial direction of the through hole 50 a. In the radial direction ofthe through hole 50 a, the connecting portion 51 of the end cover 50passes through the accommodating slot 614. The accommodating slot 614and the connecting portion 51 of the end cover 50 can be inserted andengaged with each other in the axial direction X of the through hole 50a. The part of the connecting portion 51 located outside theaccommodating slot 614 is used for locking the locking-fixing member 70and is arranged in an offset manner with the position-limiting portion612 of the position-limiting member 61 in the peripheral direction Y ofthe through hole 50 a. The position-limiting wall 511 a of the snappingslot 511 is arranged on the portion of the connecting portion 51 that islocated outside the accommodating slot 614. The position-limiting member61 is restricted by the part of the connecting portion 51 located insidethe accommodating slot 614, so that the position-limiting member 61cannot rotate relative to the connecting portion 51.

After the electrolyte is injected into the secondary battery 30 throughthe through hole 50 a, the sealing member 62 is placed on the connectingportion 51, and then the position-limiting member 61 is inserted andengaged with the connecting portion 51 in the axial direction X of thethrough hole 50 a. Then, the locking-fixing member 70 is moved in theradial direction of the through hole 50 a and snap-fitted with thesnapping slot 511 of the connecting portion 51 to lock thelocking-fixing member 70 and the connecting portion 51. Thelocking-fixing member 70 can restrict the position-limiting member 61and the sealing member 62, and restrict the position-limiting member 61and the sealing member 62 to move in the axial direction X of thethrough hole 50 a. When the electrolyte needs to be replenished into thesecondary battery 30, the locking-fixing member 70 is first moved in theradial direction of the through hole 50 a and removed from the snappingslot 511 to detach the locking-fixing member 70 from the connectingportion 51. In this way, the position-limiting member 61 and the sealingmember 62 are removed in the axial direction X of the through hole 50 a,and the through hole 50 a is exposed. The electrolyte is replenished tothe secondary battery 30 through the through hole 50 a.

In one embodiment, as shown in FIGS. 6 and 10, the end cover 50 has aconcave slot 50 b. The through hole 50 a communicates with the concaveslot 50 b. At least a part of the sealing member 62 is accommodated inthe concave slot 50 b, so that it is beneficial to reduce the size ofthe end cover assembly 40 in the axial direction X of the through hole50 a, and the energy density of the secondary battery 30 can beincreased. The concave slot 50 b is arranged in the connecting portion51 in the axial direction X of the through hole 50 a, the concave slot50 b is arranged corresponding to the middle-shaped column portion.

In an embodiment, referring to FIG. 11 to FIG. 15, the same structuresbetween the end cover assembly 40 in this embodiment and the end coverassembly 40 in the embodiment shown in FIG. 5 to FIG. 10 will not berepeated here, and the differences will be mainly described. Theconnecting portion 51 is a column-shaped boss. The snapping slot 511formed on the connecting portion 51 is an annular snapping slot 511. Thelocking-fixing member 70 has the annular structure with an opening 71,so that the locking-fixing member 70 can be snap-fitted into thesnapping slot 511 of the connecting portion 51 at different positions.The through hole 50 a is located outside the connecting portion 51, thatis, the through hole 50 a is spaced apart from the connecting portion 51in the radial direction of the through hole 50 a. The through hole 50 apenetrates the body portion 52. In an example, two or more through holes50 a are arranged to be spaced apart from one another evenly around theconnecting portion 51. Each of the position-limiting member 61 and thesealing member 62 has an annular structure. Each of theposition-limiting member 61 and the sealing member 62 is used to besleeved and connected with the connecting portion 51. The portion of theposition-limiting member 61 that is located at the side of thelocking-fixing member 70 close to the end cover 50 forms aposition-limiting portion 612, and the pressing-against portion 611 islocated at the outer periphery of the position-limiting portion 612.After the position-limiting member 61 and the sealing member 62 aresleeved on the connecting portion 51, the portion of the connectingportion 51 where the snapping slot 511 is arranged passes through theposition-limiting member 61, so that it is convenient for thelocking-fixing member 70 to be snap-fitted and fixed to the snappingslot 511 at the side of the position-limiting member 61 away from thesealing member 62. The locking-fixing member 70 exerts the compressivestress in the axial direction X of the through hole 50 a to theposition-limiting portion 612 from the side of the position-limitingportion 612 away from the sealing member 62, so that thepressing-against portion 611 exerts the compressive stress in the axialdirection X of the through hole 50 a to the sealing member 62, therebycompressing and fixing the sealing member 62. At least a part of thesealing member 62 is arranged between the pressing-against portion 611and the end cover 50, and seals all the through holes 50 a.

In an embodiment, referring to FIG. 11 and FIG. 15, a concave slot 50 bis formed on the body portion 52 of the end cover 50. The through hole50 a communicates with the concave slot 50 b. The connecting portion 51is arranged at a bottom of the concave slot 50 b. The connecting portion51 is the column-shaped boss protruding from the body portion 52. Afterthe sealing member 62 is sleeved on the connecting portion 51, at leastpart of the sealing member 62 is accommodated in the concave slot 50 b.The part of the sealing member 62 located in the concave slot 50 b cancontact with a bottom wall and a side wall of the concave slot 50 b andmaintain a sealing-fiting state, so that it is beneficial to improve thereliability and stability of the sealing between the sealing member 62and the end cover 50. In some embodiments, the position-limiting member61 and the sealing member 62 are integrally located in the concave slot50 b.

After the electrolyte is injected into the secondary battery 30 throughthe through hole 50 a, the sealing member 62 and the position-limitingmember 61 are sequentially sleeved on the connecting portion 51, thelocking-fixing member 70 is moved in the radial direction of the throughhole 50 a and snap-fitted with the snapping slot 511 of the connectingportion 51 to lock the locking-fixing member 70 and the connectingportion 51. The locking-fixing member 70 can restrict theposition-limiting member 61 and the sealing member 62, and restrict theposition-limiting member 61 and the sealing member 62 from moving in theaxial direction X of the through hole 50 a. When the electrolyte needsto be replenished to the secondary battery 30, the locking-fixing member70 is first moved in the radial direction of the through hole 50 a andremoved from the snapping slot 511 to detach the locking-fixing member70 from the connecting portion 51. In this way, the position-limitingmember 61 and the sealing member 62 are removed in the axial direction Xof the through hole 50 a, and the through hole 50 a is exposed. Theelectrolyte is replenished to the secondary battery 30 through thethrough hole 50 a.

The embodiment of the present application further provides aliquid-injection method for the secondary battery 30, including

-   -   providing the end cover 50 that includes the through hole 50 a        and the connecting portion 51,    -   injecting electrolyte through the through hole 50 a;    -   providing the sealing assembly 60;    -   mounting the sealing assembly 60 to the end cover 50, in which        the sealing assembly 60 covers the through hole 50 a;    -   providing the locking-fixing member 70, and moving the        locking-fixing member 70 toward a direction close to the        connecting portion 51 in the radial direction of the through        hole 50 a, so that the locking-fixing member 70 locks the        connecting portion 51 to restrict the end cover 50 from being        separated from the sealing assembly 60, and the sealing assembly        60 maintains in a sealing state.

In an embodiment, when the electrolyte needs to be replenished to thesecondary battery 30, the locking-fixing member 70 is moved toward adirection away from the connecting portion 51 in the radial direction ofthe through hole 50 a, so that the locking-fixing member 70 and theconnecting portion 51 are unlocked to separate the locking-fixing member70 from the end cover 50, so as to perform corresponding operations onthe sealing assembly 60.

In an embodiment, after the locking-fixing member 70 is moved toward thedirection away from the connecting portion 51 in the radial direction ofthe through hole 50 a, the liquid-injection method further includes:removing the sealing assembly 60 from the end cover 50, so that thethrough hole 50 a can be opened, and the electrolyte can be replenishedinto the secondary battery 30 through the through hole 50 a. Aftercompleting the electrolyte replenishment work, the sealing assembly 60is remounted on the end cover 50 and covers the through hole 50 a. Thenthe locking-fixing member 70 locks the connecting portion 51, so thatthe sealing assembly 60 can maintain in the sealing state.

The embodiment of the present application further provides aliquid-injection device for injecting the electrolyte into the secondarybattery 30, including a liquid injection component and adetaching-and-mounting component of the locking-fixing member. Theliquid injection component is configured to inject the electrolyte intothe through hole 50 a. The dismounting-and-mounting component of thelocking-fixing member is configured to move the locking-fixing member 70toward the direction close to the connecting portion 51 in the radialdirection of the through hole 50 a in the unlocked state, so that thelocking-fixing member 70 locks the connecting portion 51 to restrict theend cover 50 from being separated from the sealing assembly 60. Or thedismounting-and-mounting component of the locking-fixing member isconfigured to move the locking-fixing member 70 toward the directionaway from the connecting portion 51 in the radial direction of thethrough hole 50 a, so that the locking-fixing member 70 and theconnecting portion 51 are unlocked. The dismounting-and-mountingcomponent of the locking-fixing member can move the locking-fixingmember 70 in the radial direction of the through hole 50 a, so that thelocking-fixing member 70 and the connecting portion 51 can be switchedbetween the locked state and the unlocked state.

In an embodiment, the liquid-injection device further includes adismounting-and-mounting component of the sealing assembly. Thedismounting-and-mounting component of the sealing assembly is configuredto mount the sealing assembly 60 on the end cover 50, or dismount thesealing assembly 60 from the end cover 50.

The liquid-injection device in the embodiments of the presentapplication can be used in conjunction with the end cover assembly 40 inthe above embodiment, thereby improving the automation control degree ofan electrolyte replenishing process of the secondary battery 30,reducing the manual labor intensity, and improving the workingefficiency of the electrolyte replenishing process.

Although the present application has been described with reference tosome embodiments, various modifications can be made to the presentapplication and the components in the present application can bereplaced with equivalents without departing from the scope of thepresent application. In particular, as long as there is no structuralconflict, various technical features mentioned in the variousembodiments can be combined in any way. The present application is notlimited to the specific embodiments disclosed in the text, but includesall technical solutions falling within the scope of claims.

What is claimed is:
 1. An end cover assembly for a secondary battery,comprising an end cover, provided with a through hole for injectingelectrolyte therethrough and comprising a connecting portion; a sealingassembly, configured to seal the through hole; a locking-fixing member,configured to be movable relative to the connecting portion in a radialdirection of the through hole, so as to realize switching between alocked state and an unlocked state of the locking-fixing member and theconnecting portion, wherein in the locked state, the locking-fixingmember presses against the sealing assembly to restrict the end coverfrom being separated from the sealing assembly; in the unlocked state,the end cover and the sealing assembly are separable to allow theelectrolyte to be injected from the through hole.
 2. The end coverassembly according to claim 1, wherein the locking-fixing membercomprises an opening and an accommodating space communicating with eachother, and the connecting portion is configured to enter theaccommodating space through the opening, or the connecting portion isconfigured to be separated from the accommodating space through theopening.
 3. The end cover assembly according to claim 1, wherein thelocking-fixing member is snap-fitted with the connecting portion, sothat the locking-fixing member and the connecting portion are in thelocked state.
 4. The end cover assembly according to claim 3, whereinthe connecting portion is provided with a snapping slot, and at leastpart of the locking-fixing member is located in the snapping slot torestrict the locking-fixing member from moving in an axial direction ofthe through hole.
 5. The end cover assembly according to claim 4,wherein the snapping slot comprises a position-limiting wall configuredto resist against the locking-fixing member in the axial direction. 6.The end cover assembly according to claim 3, wherein the sealingassembly comprises a position-limiting member and a sealing member, thesealing member seals the through hole, and the sealing member isarranged between the position-limiting member and the end cover.
 7. Theend cover assembly according to claim 6, wherein the position-limitingmember comprises a pressing-against portion and a position-limitingportion, the pressing-against portion is connected to theposition-limiting portion and covers at least a part of the sealingmember, and the locking-fixing member presses against theposition-limiting portion to restrict the end cover from being separatedfrom the sealing assembly.
 8. The end cover assembly according to claim7, wherein the end cover further comprises a body portion, and theconnecting portion is a boss protruding from a surface of the bodyportion.
 9. The end cover assembly according to claim 8, wherein thethrough hole is located outside the connecting portion and penetratesthe body portion in its own axial direction; each of theposition-limiting member and the sealing member has an annular structureand is sleeved and connected to the connecting portion.
 10. The endcover assembly according to claim 8, wherein the through hole penetratesthe connecting portion and the body portion in its own axial direction,and at least part of the sealing member is located at a side of theconnecting portion in the axial direction.
 11. The end cover assemblyaccording to claim 10, wherein the position-limiting member furthercomprises an accommodating slot and a supporting portion connecting tothe pressing-against portion and the position-limiting portion, and theaccommodating slot penetrates the supporting portion in the radialdirection; the connecting portion passes through the accommodating slot,and a portion of the connecting portion located outside theaccommodating slot is misaligned with the position-limiting portion in aperipheral direction of the through hole, and is configured to be lockedwith the locking-fixing member.
 12. The end cover assembly according toclaim 6, wherein the end cover comprises a concave slot, the throughhole is communicated with the concave slot, and at least part of thesealing member is accommodated in the concave slot.
 13. A secondarybattery, comprising the end cover assembly according to claim
 1. 14. Abattery module, comprising the secondary battery according to claim 13.15. An apparatus comprising the secondary battery according to claim 13,the secondary battery being configured to supply electrical power.
 16. Aliquid-injection method for a secondary battery, comprising providing anend cover that comprises a through hole and a connecting portion,injecting electrolyte through the through hole; providing a sealingassembly; mounting the sealing assembly to the end cover; providing alocking-fixing member, and moving the locking-fixing member toward adirection close to the connecting portion in a radial direction of thethrough hole, so that the locking-fixing member locks the connectingportion to restrict the end cover from being separated from the sealingassembly.
 17. The liquid-injection method according to claim 16, furthercomprising moving the locking-fixing member toward a direction away fromthe connecting portion in the radial direction of the through hole, soas to unlock the locking-fixing member and the connecting portion, andseparate the locking-fixing member from the end cover.
 18. Theliquid-injection method according to claim 17, after the moving thelocking-fixing member in the direction away from the connecting portionin the radial direction of the through hole, the method furthercomprising removing the sealing assembly from the end covet
 19. Aliquid-injection device, for injecting the electrolyte into thesecondary battery according to claim 13, comprising a liquid injectioncomponent, configured to inject the electrolyte into the through hole;and a dismounting-and-mounting component of the locking-fixing member,configured to move the locking-fixing member toward a direction close tothe connecting portion in the radial direction of the through hole inthe unlocked state, so that the locking-fixing member locks theconnecting portion to restrict the end cover from being separated fromthe sealing assembly; or configured to move the locking-fixing membertoward a direction away from the connecting portion in the radialdirection of the through hole, so that the locking-fixing member and theconnecting portion are unlocked.
 20. The liquid-injection deviceaccording to claim 19, further comprising a dismounting-and-mountingcomponent of the sealing assembly, configured to mount the sealingassembly on the end cover, or dismount the sealing assembly from the endcover.